A groove in the form of welded joints

Pipeline construction welding groove type commonly used as an API standard 30 ° V-groove, suitable for manual welding. But for large-diameter, thick-walled steel pipe, this type of weld filler metal type groove joints large, labor-intensive and not suitable for automatic welding of the weld, usually semi-automatic welding with a 23 ° V-groove, automatic welding with narrow gap compound groove pattern.

2 Preheat and interpass temperature

The purpose of preheating the base metal is slow and reduce the stress state of the root weld root of the cooling rate to prevent cold cracking. Construction of the pipeline welding preheat temperature range should consider the strength of base metal, and properties changes of diameter and wall thickness, and welding materials, hydrogen and other factors. For multi-layer thick-walled pipe welding, the weld must also consider the control layer to control the temperature of the cooling rate near seam zone. Interpass temperature and preheat temperature is generally similar. To avoid overheating in the near seam zone under the premise of a higher temperature to prevent multi-layer cold Welding Electrode.

3 welding wire energy

Welding heat input to be taken into account to determine the composition of the base material, welding material type of drug skin (cored, flux) of the metallurgical response and protective effect of shielding gas, welding preheat condition, temperature control layer case, the tube specifications , wire (bar) diameter, heat affected zone of embrittlement and softening tendencies, the desired and mechanical properties, as well as welding position, welding pass, each solder layer thickness, weld and droplet forms of the transition factors.

4 after the heat treatment and heat treatment

Pipeline construction welding welding is generally not carried out after the heat treatment and heat treatment. But in the alpine region of construction, when welding preheat and interpass temperature control is difficult to play a greater role, it is necessary to take some of welded joints after the heat and heat treatment measures to ensure the organization and performance of welded joints.

5 Other

Welding in pipeline construction process should take into account the high-intensity, large wall thickness of steel are exposed to the impact of external stress. Taking into account the ambient temperature, humidity and wind speed on the environmental impact of different methods of welding, to take the necessary measures to ensure the welding quality.

keywords:Nickel Welding Rod